Body fluid management systems for patient care

ABSTRACT

Provided are body fluid management systems for patient care that include, in operable combination, a control system assembly comprising a fluid flow detection and control subassembly, a user data interface, a patient interface assembly comprising a wearable pressure sensor subassembly having a pressure sensor in the path of said body fluid for attaching directly to a patient proximate to an anatomical marker and an orientation sensor to monitor and/or control the pressure and/or flowrate of a body fluid such as cerebrospinal fluid, blood, or urine.

CROSS-REFERENCE TO RELATED APPLICATIONS

This U.S. non-provisional patent application was filed on Sep. 3, 2021as U.S. patent application Ser. No. 17/466,301 and claims the benefit ofU.S. Provisional Patent Application No. 63/074,223, which was filed onSep. 3, 2020. The contents of U.S. Provisional Patent Application No.63/074,223 are incorporated herein by reference in their entirety.

BACKGROUND OF THE DISCLOSURE Technical Field

The present disclosure relates, generally, to the field of medicine, inparticular to medical devices, and associated procedures, for monitoringand/or controlling body fluid pressure, drainage flowrate, and patientmovement. Disclosed herein are body fluid management systems for humanand animal use, which provide real-time and integrated control of bodyfluid pressure and body fluid drainage flowrate that accommodate forfrequent changes in the orientation and/or movement of a non-stationarypatient.

Description of the Related Art

The medical benefits of managing body fluid pressures through themonitoring and controlled drainage of body fluids in a variety ofclinical scenarios have been documented in the medical literature. Thisis particularly relevant where abnormal displacement, change in vesselwall compliance, excess production, or impaired natural drainagechannels may cause an accumulation of body fluid within a single organor body compartment. Excess body fluid within a single body compartmentcan cause elevated pressures, especially in low compliance conditions.Compartment syndrome is an elevation of intercompartmental pressure to alevel that impairs circulation resulting in insufficient oxygenatedblood supply leading to irreversible tissue ischemia and necrosis. See,e.g., Garner, HSS J 10(2):143 (2014); Keddissi, Can. J. Respir. Ther. 55(2018); Marik, Chest 134:172-178 (2008); Trinooson, AANA J 81(5):357-368(2013); Frazee, Kidney Dis. 2:64-71 (2016); Bhave, J Am Soc Nephrol22:2166-2181 (2011); Bruce, J Neuroophthalmol. 34(3):288-294 (2014); vander Jagt, Critical Care 20:126 (2016); and Lee, Neuro-Ophthalmol.34:278-283 (2014).

Risk factors associated with distinct causes of acute compartmentsyndrome by anatomical compartment have been identified in the medicalliterature. In the extremities, a fracture has been found to be the mostcommon cause, with muscles and nerves being most at risk. In the brain,a number of causes have been identified, such as traumatic brain injury,stroke, infection, tumors, and congenital hydrocephalus. This isexplained by the Monro-Kellie Doctrine, which establishes blood,cerebrospinal fluid and brain tissue, including interstitial fluid, asthe primary variables driving pressure in the head. In the case of theperitoneal cavity, the most documented risk factor is a patient beingcritically ill. As many as 50% of critical care patients have been foundto have elevated intra-abdominal pressure (IAP) putting them at risk forreduced abdominal organ perfusion and possible organ failure.Intra-abdominal hypertension (IAH) has also been found in clinicalpractice to impact lung function. As a result, monitoring of patients atrisk for compartment syndrome has been adopted in addition to monitoringfunctions associated with treatment. See, Garner, HSS J 10(2):143(2014); Hunt, J. Trauma Manag. Outcomes 8:2 (2014); and Mokri, Neurology56(12):1746 (2001).

Gravity-based drainage of bodily fluid, including as a treatment forelevated bodily pressure has been practiced for centuries, withsignificant improvements in the prior art over time. Unrestricteddrains, such as urinary catheters, are intended to fully drain fluidfrom a body compartment and have been in use for 3500 years. Controlledpartial drainage of cerebrospinal fluid to relieve pressure on the brainwas first documented in 1744 by Claude-Nicholas Le Cat and methods werecaptured in the art by William Williams Keen in 1890. See, Feneley, J.ME&T 39(8):459 (2015) and Srinivasan, J. Neurosurgery 120:228 (2014).

The art was further advanced in 1927 with the addition of fluid pressuremeasurement to bodily fluid drainage with the introduction of themanometer. Manometers utilize the differential height of a column offluid to measure pressure. When used in a medical context, apole-mounted manometer is aligned to the height of an externalanatomical marker with demonstrated clinical approximation to thecompartment pressure being measured. In the case of intercranialpressure, the external auditory meatus or tragus of the ear is used whenpatient is in the supine position to approximate the Foramen of Monro inthe brain. When measuring arterial pressure, the midaxillary line of thefourth intercostal space is typically used to approximate the heart. Thedevice is then opened to atmospheric pressure to “zero” the system,which is to set the baseline level of the manometer from which thedifferential in the system will be determined. See, Srinivasan, J.Neurosurgery 120:228 (2014) and Muralidharan, Surg Neural Int 6(Supp6):S271 (2015).

Further advancements in the art allowed for manometers to be used as asingle variable Boolean to control drainage of cerebrospinal fluid (CSF)based on the patient pressure being above or below a single targetvalue. In this case, the outlet end is raised to the height of thetarget intracranial pressure (ICP) with the inlet end attached to alumbar or ventricular catheter. When the pressure in the targetcompartment such as the skull or spinal column exceeds the back pressurecreated by the height of the water column in the outlet end,cerebrospinal fluid flows until balance is restored. In this way, thisanalog system is able to drain body fluid until the system reachestarget pressure. See, Srinivasan, J. Neurosurgery 120:228 (2014) andMuralidharan, Surg Neurol Int 6(Supp 6):S271 (2015).

While the use of manometers to control CSF drainage in this binaryfashion is still common practice, external pressure transducerassemblies are now often connected to the outlet end of the manometerfluid line via a stopcock. When connected to pressure monitoringequipment, such as that used for invasive arterial blood pressuremonitoring, this combination of products allows for intermittentmeasurement of the ICP value and visualization of the ICP waveform. Thisis accomplished by a clinical user manually pausing drainage andmechanically redirecting fluid to the pressure monitoring system usingthe stopcock.

Despite advances in the art over the last hundred years, limitations andrisks present in existing systems represent an unmet need in the art ofbodily fluid management systems. Because manometers are dependent onalignment of pole-mounted fluid column height to the anatomicalreference, these systems are dependent on stationary patients. Given thelow-pressure column heights relative to the height of the patientanatomy, manometers are very sensitive to patient position and movement.Even minor changes in patient position such as turning the head,adjusting the patient to reduce pressure injuries, or changes in head ofbed positioning can result in rapid over/under drainage leading todisability or death. As a result, these systems must be constantlymaintained and adjusted to compensate for any patient movement. Often itis logistically simpler to keep the patient sedated, which presentsnumerous medical risks and otherdrawbacks for the patient, family, andhealthcare provider. Even so, the risk inherit in manometer-baseddrainage necessitates constant clinical supervision. Medicalpublications have pointed to the improved outcomes possible with earlymobility post-stroke and how to work around existing technologylimitations to do so. This indicates that an invention more conducive topatient movement could contribute to lower rates of long-termdisability. See, e.g., Azuh, Am J Med 129(8):866 (2016) and Mulkey, JNeuroscience 46(3):153 (2014).

More broadly, manometers lack the ability for a user to select a desiredflowrate and current practice involves manually adjusting the targetpressure up and down until a desired flowrate is approximated achievedindirectly. Manometers do not monitor drainage volume or provide anyclosed-loop behavior. They require visual estimation and manualannotation of drained volume by the clinical user rather than automated,quantitative monitoring and reporting. In clinical use, this is known toresult in varying levels of precision dependent on user technique.Furthermore, manometer drainage systems suffer from highly variableresistance to flow, which causes inconsistent and unreliable drainage—aphenomenon that is well documented in public training materials for suchdevices. In these systems, drainage should initiate anytime the inletpressure to the manometer exceeds the back pressure created by theheight of the water column in the manometer.

For example, if a patient has been maintained at equilibrium at 10cmH2O, then ICP suddenly spikes to 15 cmH2O, the manometer shouldoverflow and begin to drain to restore pressure equilibrium to the 10cmH2O set point. However, in order to initiate (or maintain) flow in thedrainage line, the fluid must overcome the resistance to flow along theentire length of the drain line. Since resistance to flow can bestrongly influenced by bits of tissue, air gaps, or large bubbles in thedrain line, micro bubbles adhered to the inner wall of the drain line,manufacturing variation in components and assembly operations(tolerances, adhesive pushout during bonding operations, etc.), and avariety of other factors, drainage may not initiate until after ICP hasincreased considerably beyond the desired set point, and may cease wellbefore the set point equilibrium is restored. Because ICP values are sosmall in absolute terms, the resistance to flow can be quite largerelative to clinically significant ICP changes. The observed unreliableand inconsistent drainage is largely unavoidable due to the physics ofmanometer-based drains.

Manometers and external pressure transducers can be paired (as is oftendone clinically) to construct a fluid management system that providesfluid pressure monitoring as well as fluid drainage; however, such fluidmanagement systems cannot be used to simultaneously measure fluidpressure while controlling fluid drainage. As a result, this pairinglacks the ability to offer continuous monitoring and drainage,increasing the risk of complications not being detected in a timelymanner.

The existing art does include the recent addition of new more complexcatheters that allow for pressure transducer assemblies to be connectedto the catheter in parallel with the drainage manometer to allow forcontinuous monitoring. This approach creates non-communicating, parallelactivities displayed to the user, rather than an integrated system. Thisapproach still depends on a manometer to control drainage based on aBoolean threshold, including the manometer limitations therein.

Existing external pressure monitoring technologies suffer from driftresulting in a lack of accuracy that is particularly relevant in theanatomical compartments for which the pressure is represented by smallnumerical values and even minor changes within a narrow range are ofclinical significance. In most mammals, this would include a variety ofcompartment pressures such as ICP, CVP, IAP and the like. These valuesare measured in millimeters of mercury (mmHg) or centimeters of water(cmH2O). When considering ICP in humans for example, infant normal isoften expressed as <5 mmHg while supine adults are typically 7-15 mmHgdepending on the patient. In the case of IAP, normal adult values are5-7 mmHg and in children are typically 0-5 mmHg. This is in comparisonwith arterial pressure values in a much wider range of 60-120 mmHg. Inclinical practice, they have a typical accuracy on the order of ±2 mmHgin practical use due to sensor drift. However, clinically significantdeviations in various pressure parameters of interest (ICP, CVP, IAP,etc.) are on the order of a few cmH2O. Therefore, the results derivedfrom these sensors are at best of delayed clinical use until the patientworsens further, and at worst misleading. Given the importance of thebrain, heart and other organ function to not only recovery from acuteillness, but long-term quality of life of the patient, early detectionof true changes in values would be a significant improvement over theprior art.

Diaphragm-style transducers more recently introduced to obtainclinically relevant accuracy generally have lower natural resonantfrequencies and may suffer from undesired oscillations induced byphysiological functions such as a heartbeat.

Due to inability of all these systems to detect sensor drift or failure,such systems necessarily rely on complicated schemes, custom sensorconfigurations, or constant manual recalibration to temporarily achievethe precision and accuracy required to provide existing clinicalbenefit. These labor-intensive accommodations along with the risks theyintroduce have throttled more widespread adoption of the core bodilyfluid drainage technology.

Another shortcoming of the existing inventions is in the area ofperfusion pressure (i.e., the net pressure of fluid passing through thecirculatory system or lymphatic system into an organ or tissue(generally, an anatomical compartment). Perfusion pressure includescerebral perfusion pressure (CPP), which is the net pressure gradientcausing cerebral blood flow to the brain (brain perfusion). It must bemaintained within narrow limits because too little pressure could causebrain tissue to become ischemic (having inadequate blood flow), and toomuch could raise intracranial pressure (ICP).

Measurements of perfusion pressure are clinically relevant to managingcompartment pressure and preventing a compartment syndrome in whichincreased pressure within one of the body's anatomical compartmentsresults in insufficient blood supply to tissue within that space. See,Peitzman, The Trauma Manual: Trauma and acute Care Surgery (LippincottWilliams & Wilkins, 2012)). Individual fluid pressures are often inputsinto the clinical management of perfusion pressure and are used in themathematical formula for calculating perfusion pressure (i.e. SpinalFluid Perfusion Pressure=MAP−lumbar pressure). There remains a need inthe art for automation of activities and calculations, which arecurrently being performed by a clinician such as a nurse using multiplesystems and human analysis.

When calculating perfusion pressure, the MAP value is typically obtainedfrom the invasive arterial blood pressure monitor which nurses aretrained to align with the midaxillary line and fourth intercostal spaceas these are the anatomical markers for the location of the heart. Whilethe patient is in the supine position, the height of the fluid columndriving pressure is going to be fairly constant across the horizontalplane. However, patients are often adjusted to 30-degree Head of Bedposition. In this position, MAP values are going to be calculateddifferently if referencing the anatomical marker of the compartmentfluid versus that of the heart. The inconsistencies in the practice andeven among nurse educators create variability in the calculated CPPvalues due to patient position. This can lead to adverse outcomes andthwart medical innovation.

Furthermore, perfusion pressure is calculated by a patient monitor asthe result of multiple devices providing values in parallelunidirectionally to the display. This monitoring and communicationfunction is occurring completely separate from drainage. The existingart does not support integrated multi-modal analysis and management. Ithas no ability to control drainage based on these calculated perfusionpressure values.

When considering perfusion pressure in clinical context, the inabilityin the prior art to sense or characterize patient movement results inunexpected opportunities for improvement beyond real-time drainageaccuracy. For example, current systems cannot distinguish betweenclinically indicative changes in compartment pressure versus expected,predictable changes due to change in patient position or movement. Thiscurrently requires immediate nursing response to alarms if in use,creating alarm fatigue. It also requires manual annotation in thepatient data in order for trend information to be useful in assessingpatient's condition. It does not offer an efficient method for mappingimpact of patient movement or position on compartment pressures.Finally, it obscures otherwise useful datasets that could advance theart in terms of bodily fluid management or broader medicalunderstanding.

When the primary purpose of bodily fluid drainage is not to achieve aspecific pressure value, other analog devices are available for use indraining body fluids. Excluding the use of syringes used in manual fluidsampling, the existing systems are also gravity-based and can bedescribed as volume-limiting drains and unrestricted drains.Volume-limiting drains are fully disposable analog catheters that dependon the mechanical constraint of a full bulb to stop drainage. Incomparison with manometers, which are typically connected to a drain bagthat can hold more than 500 ml of fluid, volume-limiting catheters mayonly have a capacity for 30 ml and are removed upon completion ofdraining 30 ml. Unrestricted drains, such as urinary catheters, surgicaldrains, or wound management devices, are also analog catheters which areintended to fully drain fluid from a body compartment. They may beindwelling or used intermittently. Neither volume-limiting drains norunrestricted drains can be used to measure pressure, and neither candrain fluids based upon a target pressure. Both also lack the abilityfor a user to designate a desired flowrate despite speed of drainagebeing a significant variable clinicians would prefer to control bypatient condition. These various analog drain systems also requirevisual estimation of volume drained using markings on the drain bag asthey lack quantitative calculation and reporting of volume drained.

While existing body fluid management systems provide some clinicalbenefit, particularly when multiple devices are used in combination, theneed remains for integrated systems for real-time fluid pressuremonitoring and control of fluid drainage that allow for patient movementwithout requiring constant medical oversight or intervention. Thus,there remains an unmet need in the art for body fluid management systemsthat permit the monitoring and management of body fluid pressures innon-stationary patients.

SUMMARY OF THE DISCLOSURE

The present disclosure fulfills unmet needs in the art, and furtherrelated advantages over existing technologies, by providing body fluidmanagement systems that employ digital technologies to permit real-timemonitoring and control of body fluid pressures or drainage flowrateswhile allowing or accounting for patient movement. Use of the varioussensing modalities in combination enables improved accuracy, control,data capture, patient safety, and patient mobility relative to thesystems described in the prior art. Furthermore, the integration ofdrainage control and multi-fluid pressure monitoring into a singlesystem enables automated therapeutic intervention based on derivedphysiological parameters, such as perfusion pressure, which isunprecedented in the art.

Thus, within certain embodiments, the present disclosure provides bodyfluid management systems, comprising: a control system assembly forreal-time monitoring of body fluid pressure and integrated control ofbody fluid drainage and a patient interface assembly comprising awearable pressure sensor subassembly for attaching proximate to apatient anatomical marker, said wearable pressure sensor subassemblycomprising a pressure sensor in the path of said body fluid and anorientation sensor. In some aspects, control system assemblies areconfigured for detecting changes in body fluid pressure, patientmovement, or patient orientation based on inputs from the patientinterface assembly. In other aspects, control system assemblies areconfigured with an algorithm to make corrective adjustments to theflowrate of body fluid drainage or assert an alarm based on user-definedsettings.

In certain aspects of these embodiments, body fluid management systemscomprise a control system assembly having a fluid flow detection andcontrol subassembly in operable communication with a user interfacesubassembly including graphical user interface, such as a graphical userinterface configured to display a pressure waveform. In related aspects,the fluid flow detection and control subassembly comprises, in operablecommunication, a flowrate control actuator, a flow shutoff actuator, anda body fluid flow detector.

In other aspects of these embodiments, body fluid management systemscomprise a wearable pressure sensor subassembly having a plurality ofpressure sensors in the body fluid path, wherein the plurality ofpressure sensors comprises a first pressure sensor and a second pressuresensor at a fixed spacing distance and wherein the plurality of pressuresensors and said orientation sensor are configured on a rigid member fordetecting drift in one or more of said plurality of pressure sensorsbased on a disparity between an anticipated differential pressurebetween the first pressure sensor and the second pressure sensor and anactual differential pressure between the first pressure sensor and thesecond pressure sensor.

In related aspects of these embodiments, body fluid management systemscomprise a patient interface assembly having a body fluid drip chamber,a fluid drainage cartridge for connecting to said control systemassembly, a drain tube for body fluid drainage, and an electrical cablefor passing signals from said wearable pressure sensor subassembly tosaid fluid drainage cartridge.

In certain of the body fluid management systems disclosed herein, thebody fluid is cerebrospinal fluid (CSF) and the control system assemblyis configured for real-time monitoring of intracranial pressure (ICP)and integrated control of CSF drainage. In related aspects, the patientinterface assembly comprises a drain tube that is configured at itsproximal end for connecting to a ventricular catheter and a wearablepressure sensor subassembly that is configured for attaching proximateto a patient external auditory meatus (EAM).

In related embodiments, the body fluid management systems disclosedherein further comprise an infusion source configured for connecting tothe control system assembly via a bidirectional infusion and drainagetube, wherein the control system assembly comprises a pump for pumpingliquid from the infusion source to a body cavity. In certain aspects ofthese embodiments, the control system assembly is configured forreal-time monitoring of intra-abdominal pressure and the patientinterface assembly comprises a drain tube that is configured at itsproximal end for connecting to a urinary catheter. In other aspects, thebody cavity is a bladder.

In further embodiments of the present disclosure are provided systemsfor determining perfusion pressure, that comprise a control systemassembly for real-time monitoring of body fluid pressure and integratedcontrol of body fluid drainage from a body compartment, wherein thecontrol system assembly is configured with a pump for pumping a fluidfrom an infusion source into secondary fluid line described below, andan algorithm to respond to signals from a first wearable pressure sensorsubassembly and a second wearable pressure sensor subassembly to makecorrective adjustments to the flowrate of body fluid drainage or assertan alarm based on user-defined settings.

The systems for determining perfusion pressure according to theseembodiments comprise a patient interface assembly having a primary fluidline that is configured at its proximal end for connecting to a catheterinserted into said body fluid compartment and at its distal end forconnecting to a detachable fluid drainage reservoir, a first wearablepressure sensor subassembly for attaching proximate an anatomical markerfor the body fluid compartment, wherein the first wearable pressuresensor subassembly comprises a first pressure sensor in the path of thebody fluid and an orientation sensor that are configured for detectingchanges in body fluid pressure and patient movement and orientation andsignaling those changes to said control system assembly, a secondaryfluid line that is configured at its proximal end for connecting to anarterial catheter and at its distal end for connecting to said infusionsource, a second wearable pressure sensor subassembly for attachingproximate an anatomical marker for monitoring blood pressure, whereinsaid second wearable pressure sensor subassembly comprises a secondpressure sensor in the path of said blood and an orientation sensor thatare configured for detecting changes in blood pressure and patientmovement and orientation and signaling those changes to said controlsystem assembly, wherein perfusion pressure is calculated based on themeasured blood pressure and body compartment fluid pressure.

Within certain aspects of these embodiments, control system assembliescomprise a fluid flow detection and control subassembly in operablecommunication with a user interface subassembly including graphical userinterface, such as a graphical user interface that is configured todisplay a pressure waveform. In related aspects fluid flow detection andcontrol subassemblies comprise, in operable communication, a flowratecontrol actuator, a flow shutoff actuator, and a body fluid flowdetector.

Within other aspects of these embodiments, the first wearable pressuresensor subassembly comprises a first pressure sensor and a secondpressure sensor in a body fluid path, wherein the first and secondpressure sensors are at a fixed spacing distance, and wherein the firstand second pressure sensors and the orientation sensor are configured ona rigid member for detecting drift in the first pressure sensor or thesecond pressure sensor based on a disparity between an anticipateddifferential pressure between the first and second pressure sensors andan actual differential pressure between the first and second pressuresensor.

Within further aspects of these embodiments, the second wearablepressure sensor subassembly comprises a third pressure sensor and afourth pressure sensor in the blood path, wherein the third and fourthpressure sensors are at a fixed spacing distance, and wherein the thirdand fourth pressure sensors and the orientation sensor are configured ona rigid member for detecting drift in the third pressure sensor or thefourth pressure sensor based on a disparity between an anticipateddifferential pressure between the third and fourth pressure sensors andan actual differential pressure between the third and fourth pressuresensors.

Within related aspects, the patient interface assembly comprises a bodyfluid drip chamber, a fluid drainage cartridge for connecting to thecontrol system assembly, a drain tube for body fluid drainage, and anelectrical cable for passing signals from the wearable pressure sensorsubassembly to the fluid drainage cartridge.

Within other aspects, the body fluid is cerebrospinal fluid (CSF), thecontrol system assembly is configured for real-time monitoring ofintracranial pressure (ICP) and integrated control of CSF drainage, thepatient interface assembly comprises a drain tube that is configured atits proximal end for connecting to a ventricular catheter, and thewearable pressure sensor subassembly is configured for attachingproximate to a patient external auditory meatus (EAM).

Within further aspects, systems according to these embodiments comprisea connection for an infusion source and a bidirectional infusion anddrainage tube, wherein the control system assembly comprises a pump forpumping liquid from the infusion source to a body cavity. In relatedaspects, the control system assembly is configured for real-timemonitoring of intra-abdominal pressure and the patient interfaceassembly comprises a drain tube that is configured at its proximal endfor connecting to a urinary catheter. In other aspects, the body cavityis a bladder.

The present disclosure also provides wearable pressure sensorsubassemblies that comprise a plurality of pressure sensors in the pathof a body fluid and an orientation sensor, wherein the plurality ofpressure sensors and the orientation sensor are configured for detectingchanges in body fluid pressure, patient movement, or patientorientation. In certain aspects, the wearable pressure sensorsubassembly is configured for attaching proximate to a patientanatomical marker. In other aspects, the plurality of pressure sensorscomprises a first pressure sensor and a second pressure sensor at afixed spacing distance and the plurality of pressure sensors and theorientation sensor are configured on a rigid member for detecting driftin the first pressure sensor and the second pressure sensor based on adisparity between an anticipated differential pressure between the firstpressure sensor and the second pressure sensor and an actualdifferential pressure between the first pressure sensor and the secondpressure sensor.

Within further aspects of these embodiments, wearable pressure sensorsubassemblies are configured for attaching to a patient externalauditory meatus (EAM) and the plurality of pressure sensors and theorientation sensor are configured for detecting changes in intracranialpressure (ICP).

The various fluid management systems disclosed herein provide particularadvantages for the monitoring and control of body fluid pressures andflowrates in mobile patients where real-time monitoring of body fluidpressures and integrated control of body fluid drainage flowrates yieldsimproved patient care through enhanced automation, greater opportunityfor patient mobility, and reduced reliance on health care professionalsfor continual fluid pressure monitoring and system calibration as isrequired of fluid pressure management systems that are currentlyavailable in the art.

These and other related aspects of the present disclosure will be betterunderstood in view of the following drawings and detailed description,which exemplify certain aspects of the various embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

Certain aspects of the present disclosure will become more evident inreference to the drawings, which are presented for illustration, notlimitation.

FIG. 1 is a line drawing showing a front perspective view of a controlsystem assembly according to certain embodiments of the presentlydisclosed body fluid management systems. Control system assembliesaccording to these embodiments are configured for use in operablecombination with a patient interface assembly (such as is depicted inFIG. 4 and described in further detain herein).

FIG. 2 is a line drawing showing a rear perspective view of a controlsystem assembly according to certain embodiments of the presentlydisclosed body fluid management systems.

FIG. 3 (FIG. 3A and FIG. 3B) are line drawings showing perspective viewsof an exemplary flowrate control actuator for use in control systemassemblies according to certain embodiments of the presently disclosedbody fluid management systems. The flowrate control actuator shown inFIG. 3A employs a pinch head that is fixedly attached to a leadscrew.The flowrate control actuator shown in FIG. 3B employs a spring-loadedpinch head.

FIG. 4 is a line drawing showing a perspective view of a patientinterface assembly according to one embodiment of the presentlydisclosed portable systems for managing body fluid pressure and drainageflowrates. As shown in FIG. 4 , patient interface assemblies areconfigured for removable insertion into, and operable combination with,a control system assembly, such as, for example, a control systemassembly as depicted in FIG. 1 and FIG. 2 .

FIG. 5 is a line drawing that depicts an embodiment of the patientinterface assembly as it relates to the patient anatomy, wherein thepressure sensor assembly is sutured directly to the patient's skinon thehead substantially proximate to a known anatomical marker.

FIG. 6 depicts alternate embodiments in which the pressure sensorassembly is constrained near an anatomical marker by means of a wearabledevice.

FIG. 7 depicts alternate embodiments in which the pressure sensorassembly is constrained near an anatomical marker by means of a wearabledevice.

FIG. 8 is a line drawing of an exemplary wearable pressure sensorsubassembly for use in certain embodiments of the patient interfaceassemblies disclosed herein.

FIG. 9 (FIG. 9A and FIG. 9B) is a schematic representation of a wearablepressure sensor subassembly according to certain embodiments of thepresent disclosure.

FIG. 10 depicts one embodiment of the presently disclosed body fluidmanagement systems, which is configured for managing intracranialpressure (ICP) and cerebrospinal fluid (CSF) drainage, wherein a patientinterface assembly is connected to a ventricular catheter at a proximalend of a drain tube.

FIG. 11 depicts one embodiment of the presently disclosed body fluidmanagement systems, in which the patient interface assembly isconfigured to connect to an indwelling urinary catheter, and the controlsystem assembly is configured to activate the pumping mechanism toperiodically flush the bladder and urinary catheter.

FIG. 12 depicts one embodiment of the presently disclosed body fluidmanagement systems that is configured to obtain the necessary inputs tocalculate real-time CPP wherein the systems include a plurality ofwearable sensor assemblies, wherein a first wearable sensor assembly isaffixed to the patient substantially proximate to an anatomical markerappropriate for monitoring ICP and a second wearable sensor assembly isaffixed to the patient substantially proximate to an anatomical markerappropriate for monitoring blood pressure.

DETAILED DESCRIPTION OF THE DISCLOSURE

The present disclosure provides body fluid management systems thatemploy digital technologies to permit real-time monitoring and controlof body fluid pressures or drainage flowrates while allowing oraccounting for patient movement. Within certain embodiments, portablesystems according to the present disclosure comprise, in operablecombination, (1) a control system assembly and (2) a patient interfaceassembly. The body fluid management systems disclosed herein exhibitunexpected and surprising advantages over devices and technologies thatare currently available in the art for monitoring and managing in vivofluid pressures and flowrates.

This disclosure will be better understood in view of the followingdefinitions, which are provided for clarification and are not intendedto limit the scope of the subject matter that is disclosed herein.

Definitions

Unless specifically defined otherwise herein, each term used in thisdisclosure has the same meaning as it would to those having skill in therelevant art.

As used herein, the term “body fluid” refers generally to liquids withinan extracellular compartment of the human body (i.e. extracellularfluids (ECF)), which include both interstitial fluids that are notcontained within blood vessels and intravascular fluids that arecontained within the blood vessels (such as venous fluids and arterialfluids). As used herein, “body fluids” include fluids within thetranscellular compartment, such as fluids in the tracheobronchial tree,the gastrointestinal tract, and the bladder, and includes cerebrospinalfluid and fluids within the aqueous humor of the eye.

As used herein, the term “cerebrospinal fluid” or “C SF” refers to thesodium-rich, potassium-poor tissue fluid of the brain and spinal cord.CSF supplies nutrients, removes waste products, and provides a cushionthat absorbs mechanical shock to the central nervous system. CSF isnormally watery, clear, colorless, and almost entirely free of cells. Anormal adult human has about 125-150 mL of CSF circulating within theventricular system of the brain and spine. The majority of CSF isproduced from within the two lateral ventricles.

As used herein, the term “body fluid pressure” refers generally to thepressure exerted by a “body fluid” that is contained within anextracellular compartment and includes, for example, intracranialpressure, arterial pressure, central venous pressure, andintra-abdominal pressure/bladder pressure.

As used herein, the term “body compartment pressure” refers generally tothe pressure within an extracellular compartment and includes, forexample, the pressure within the head (intracranial pressure), theabdomen (intra-abdominal pressure) and the limbs.

As used herein, the terms “compartment syndrome” and “compartmenthypertension” refer to abnormally elevated pressure within a bodycompartment. “compartment hypertension” is characterized by a lowerdisease threshold as compared to “compartment syndrome.”

As used herein, the term “intracranial pressure” or “ICP” refers to thepressure exerted by the cerebrospinal fluid (CSF) inside the skull andon the brain tissue.

As used herein, the term “arterial pressure” refers to the bloodpressure in the arterial vasculature. The term is generally synonymouswith the related term “mean arterial pressure” (MAP), which refers tothe average blood pressure in an individual over a single cardiac cycle.MAP is calculated using the systolic pressure (SP) peak during heartpumping/squeeze and diastolic pressure (DP) low during heart relaxingbetween pumps/beats, according to the expression MAP=DP+(SP−DP)/3.

As used herein, the term “central venous pressure” or “CVP” refers tothe blood pressure in the vena cava, near the right atrium of the heart.

As used herein, the term “accelerometer” refers to a type of“orientation sensor” that is capable of quantifying acceleration in oneor more axial directions, according to the inertial force of a mass andNewton's Second law, and producing a digital electrical signal (SPI,I2C, etc.) proportional to said acceleration. Such devices are usefulfor determining orientation (by measuring static acceleration due togravity) and detecting motion (by analyzing dynamic acceleration).

As used herein, the term “pressure sensor” refers to a device that iscapable of quantifying pressure (and changes in pressure) in a fluid(air, water, saline, body fluid, etc.) and producing an electricalsignal proportional to said pressure (or change in pressure). As usedherein, “pressure sensor” may refer to a device configured to measuregauge pressure or absolute pressure.

As used herein, the term “anatomical marker” refers to physiologicalattributes or features that are non-invasively identifiable, such ascephalometric landmarks, joints, or intercoastal space and the like, forwhich there may be clinical significance relative to an internalposition. Examples include: the external auditory meatus (EAM) or theglabella as anatomical markers for the brain center or Foramen of Monrooften used in the calculation of ICP, and the fourth intercostal spaceat the midaxillary line as an anatomical marker for the position of theheart.

Words and phrases using the singular or plural number also include theplural and singular number, respectively. For example, terms such as “a”or “an” and phrases such as “at least one” and “one or more” includeboth the singular and the plural. Terms that are intended to be “open”(including, for example, the words “comprise,” “comprising,” “include,”“including,” “have,” and “having,” and the like) are to be construed inan inclusive sense as opposed to an exclusive or exhaustive sense. Thatis, the term “including” should be interpreted as “including but notlimited to,” the term “includes” should be interpreted as “includes butis not limited to,” the term “having” should be interpreted as “havingat least.”

The use of the term “or” in the claims and supporting text is used tomean “and/or” unless explicitly indicated to refer to alternatives onlyor the alternatives are mutually exclusive, although the disclosuresupports a definition that refers to only alternatives and “and/or.”

Additionally, the terms “herein,” “above,” and “below,” and words ofsimilar import, when used in this application, shall refer to thisapplication as a whole and not to any particular portion of theapplication.

It will be further understood that where features or aspects of thedisclosure are described in terms of Markush groups, the disclosure isalso intended to be described in terms of any individual member orsubgroup of members of the Markush group. Similarly, all rangesdisclosed herein also encompass all possible sub-ranges and combinationsof sub-ranges and that language such as “between,” “up to,” “at least,”“greater than,” “less than,” and the like include the number recited inthe range and includes each individual member.

All references cited herein, whether supra or infra, including, but notlimited to, patents, patent applications, and patent publications,whether U.S., PCT, or non-U.S. foreign, and all technical, medical,and/or scientific publications are hereby incorporated by reference intheir entirety.

Body Fluid Management Systems

Provided herein are body fluid management systems that employ digitaltechnologies to permit real-time integrated monitoring and control ofbody fluid pressures or drainage flowrates while allowing or accountingfor patient movement.

Exemplary body fluid management systems disclosed herein are describedin reference to the management of particular body fluid(s). It will beunderstood, however, that the body fluid management systems of thepresent disclosure will find utility in the monitoring and management ofvarious extracellular and interstitial body fluids including, withoutlimitation, cerebrospinal fluid, blood, urine, wound exudate, mucus, andsemen. Furthermore, it will be understood that the body fluid managementsystems of the present disclosure will find utility in the monitoringand management of various bodily compartments including, withoutlimitation, the intracranial space, the intra-abdominal space, and theextremities.

Within certain embodiments, body fluid management systems according tothe present disclosure comprise, in operable combination, (1) a controlsystem assembly and (2) a patient interface assembly.

In certain aspects of these embodiments, the control system assembly maybe durable and the patient interface assembly may be disposable. Inother aspects, the body fluid management systems disclosed herein may befully durable with a cleanable or re-sterilizable patient interfaceassembly, or such systems may be fully disposable.

The body fluid management systems disclosed herein may be selectivelyoperable in a pressure-control mode (e.g., by utilizing a pressure setpoint), in a flowrate-control mode (e.g., by utilizing a drainageflowrate set point), or in a monitoring-only mode for pressure datacollection or user notifications (e.g., alarms) in response touser-configurable alarm thresholds.

Flowrate-control mode and pressure-control mode may both be accomplishedin the same manner: by controlling the drainage of the associated bodyfluid. This may be accomplished by means of a soft flexible tube in thepatient interface assembly that is variably or intermittently compressedby a flowrate control actuator in the control system assembly. Analgorithm may be utilized to provide closed-loop control of a flowratecontrol actuator based on inputs from various sensors in the system.

Drainage flow may be maintained by employing a drain line that issubstantially filled with fluid, and which has an outlet lower than itsinlet, whereby a siphon effect is maintained.

Drainage flowrate measurements may be accomplished by detecting fallingdrops of fluid within a chamber (drip chamber, cuvette, etc.), whereinthe drops are of a substantially known volume. In such an arrangement,the system may count the drops and calculate flowrate based on thenumber of drops over a timespan of interest (e.g., mL/hr). Drainageflowrate measurements may also be accomplished with an ultrasonicsensor, a mass flowrate sensor, or any similar sensor capable ofdirectly or indirectly measuring flow.

Pressure measurement may be accomplished by two or more disposablepressure sensors located substantially proximate to a patient anatomicalmarker wherein: the pressure sensors are located within the drainageflow channel, in direct communication with patient body fluid; thepressure sensors are co-located within a housing that is affixed to thepatient skin; the pressure sensors are rigidly mounted at a definedspacing, such that the difference of two sensor readings can becalculated to detect sensor faults (drift, sensor failure, occlusion,fouling, etc.); the orientation of the drainage flow channel is detectedby means of an orientation sensor, whereby the expected differentialpressure between two pressure sensors (based on fluid density andvertical component of sensor spacing) is calculated and used to augmentpressure sensor fault detection; stable (average) pressure is derivedfrom variable pressure readings (such as may be observed from an ICPwaveform, blood pressure systolic/diastolic pressure spikes, etc.) via aproprietary algorithm.

In certain embodiments, the system may be configured to monitor and/orcontrol pressure or flowrate of a single fluid (CSF, blood, urine,etc.). In other embodiments, the system may be configured to monitorand/or control two or more fluids or anatomical subsystems (CSF andblood; bladder pressure and intra-abdominal pressure; etc.). In certainembodiments, the system may include calculation of a derived parameter,such as perfusion pressure (CPP, APP, SCPP, etc.), and may monitorand/or control pressure or flowrate of a single fluid or bodycompartment based on said derived parameter. In certain embodiments, thesystem may include a peristaltic or similar pumping mechanism forcontrol of fluids other than the target body fluid (saline, artificialCSF, etc.) for the purposes of periodic flushing, back-pressure (as maybe the case with an arterial line), etc.

1. Control System Assemblies

Control system assemblies disclosed herein comprise, in certainembodiments, (1) a fluid flow detection and control subassembly that isin operable communication with (2) a user interface subassembly toachieve the real-time monitoring and control of body fluid pressure anddrainage. In certain aspects of these control system assemblies, thefluid flow detection and control subassembly comprises, in operablecommunication, a primary flowrate control actuator, a secondary flowshutoff actuator, and a body fluid flow sensor.

FIG. 1 and FIG. 2 are line drawings showing perspective views of anexemplary control system assembly 10 that is configured for use inoperable combination with a patient interface assembly 50 (such as isdepicted in FIG. 4 and described elsewhere herein) according to certainembodiments of the presently disclosed body fluid management systems.

As depicted in FIG. 1 , control system assembly 10 comprises fluid flowdetection and control subassembly 20 in operable combination with userinterface subassembly 40, which includes user interface 42 for receivinguser input (settings, patient information, etc.) and displaying systemsettings and outputs (set points, alarm thresholds, patient information,current or historical pressure or flowrate data, alarms, notifications,waveforms, etc.). In certain embodiments, user interface 42 may comprisea graphical display (LCD, OLED, etc.), a touchscreen (resistive,capacitive, projected capacitive, etc.), a button keypad (plastic orelastomeric buttons, membrane switch, etc.), an LED array (7-segment,individual indicators, etc.), or any similar elements suitable for entryof user inputs and display of system settings and outputs.

As depicted in FIG. 2 , control system assembly 10 comprises adjustableclamping mechanism 14 for fixation to an IV pole 11, bed rail, or othersimilar patient room furnishing. In other embodiments, control systemassembly 10 may be configured to be cart-mounted, wall-mounted, orfree-standing.

In other aspects, control system assembly 10 comprises a receptacle 12for connection to an external power source (AC mains, DC network, etc.),and may optionally include an internal power source (rechargeablebattery).

In further aspects, control system assembly 10 may include an electricalinterface (connector/socket, pogo-pin/spring-loaded contact array, etc.)for DC power distribution and electrical signal communication withpatient interface assembly 50. In other embodiments, such communicationor power distribution may be accomplished wirelessly.

In certain embodiments, fluid flow detection and control subassembly 20and user data interface subassembly 40 may each be enclosed in a set ofrigid (plastic, metal, etc.) housings and joined by pivoting mechanism48 (hinge, 4-bar linkage, etc.) so that the subassemblies may pivot openand closed with respect to one another. In certain embodiments, pivotingmechanism 48 may include a feature (over-center, cam, etc.) thatprovides one or more preferred positions (closed, fully open, etc.) toassist with installing/uninstalling fluid drainage cartridge 60. Asdepicted in FIG. 1 , hand grip 44 and hand clearance feature 24 may beincluded to facilitate operation of pivoting mechanism 48. In alternateembodiments, control system 10 may be comprised of a single set of rigidhousings enclosing both fluid flow detection and control assembly 20 anduser interface subassembly 40 such that hinge 48, hand grip 24, andother associated features, are eliminated. In such embodiments, recess32 for receiving fluid drainage cartridge 60 of patient interfaceassembly 50 may be located adjacent to graphical user interface 42.

In other aspects, fluid flow detection and control subassembly 20includes recess 32, drainage tube inlet 34, and drainage tube outlet 26for receiving fluid drainage cartridge 60 and associated drain tube 68of patient interface assembly 50 (depicted in FIG. 4 ).

In other aspects depicted in FIG. 1 , fluid flow detection and controlsubassembly 20 includes, in operable combination, primary flowratecontrol actuator 22 for controlling flowrate of a body fluid, secondaryflow shutoff actuator 30 for automatic shutoff of drainage flow in thecase of power loss or system failure, and body fluid flow detector 28for detecting drainage flowrate.

In certain embodiments, body fluid flow detector 28 may be an opticalsensor for detecting falling fluid drops (as in drops falling through adrip chamber, cuvette, or similar enclosure), a mass flow sensor, anultrasonic flow sensor, or any other similar sensor that is capable ofdetecting flow of the target body fluid with clinically-acceptableprecision and accuracy.

In certain embodiments, secondary flow shutoff actuator 30 may be a DCmotor with encoder and leadscrew, a stepper motor with leadscrew, aservo motor, a solenoid, a linear actuator, an electromagnetic latch, orany other similar actuator or latching mechanism that can be actuatedsufficiently rapidly to shut off flow in the case of power loss orsystem failure.

In certain embodiments, primary flowrate control actuator 22 may be a DCmotor with encoder and leadscrew, a stepper motor with leadscrew, aservo motor, a solenoid, a linear actuator, or any other similaractuator that either provides precise positioning for substantiallyconstant flowrate (as in the case of a motor with encoder, stepper, orservo) or can be actuated rapidly between on/off states for intermittentflow (as in the case of a solenoid).

FIG. 3A and FIG. 3B depict an exemplary primary flowrate controlactuator 22 that may be advantageously employed in control systemassembly 10 according to certain embodiments of the presently disclosedbody fluid management systems. As shown in FIG. 3A, primary flowratecontrol actuator 22 may be comprised of a stepper motor 92 withintegrated leadscrew 96 and captive leadscrew nut 94 to translate rotarymotion into linear motion. Pinch head 98 comprising pinch head tip 100may be included to interface with drain tube 68 in patient interfaceassembly 50 (depicted in FIG. 4 ). In other embodiments, pinch head 98may be replaced with spring-loaded pinch head 102 as shown in FIG. 3B toimprove flow control precision or provide substantially constant forceat the fully pinched condition regardless of any over-travel of theprimary flow control actuator.

In other embodiments, flow control or shutoff may be accomplished by arotary valve (stopcock, needle valve, etc.) in patient interfaceassembly 50 that is variably rotated by a rotary actuator (servo,stepper motor, rotary solenoid, etc.) in control assembly 10.

2. Patient Interface Assemblies

Patient interface assemblies for use in the body fluid managementsystems disclosed herein comprise, in various operable combinations: (1)a body fluid flow measurement interface, (2) a flowrate control actuatorinterface, (3) a flow shutoff actuator interface, (4) an electricalinterface, (5) a fluid drainage cartridge, (6) a drain tube, and (7) awearable pressure sensor subassembly. In certain aspects of thesepatient interface assemblies, the wearable pressure sensor subassemblycomprises, in operable communication: (1) an orientation sensor, (2) aplurality of pressure sensors, (3) an integrated flow channel, and (4) arigid or semi-rigid sensor enclosure.

FIG. 4 is a line drawing showing a perspective view of patient interfaceassembly 50 according to one embodiment of the presently disclosed bodyfluid management system, wherein patient interface assembly 50 isconfigured for removable insertion into, and operable combination with,control system assembly 10. In certain embodiments, fluid drainagecartridge 60 (comprised primarily of rigid plastic enclosures such asABS, nylon, polycarbonate, etc.) of patient interface assembly 50 may beinstalled into a corresponding recess in control system assembly 10,such as recess 32 depicted in FIG. 1 .

As depicted in FIG. 4 patient interface assembly 50 may comprise flowmeasurement interface 52 (drip chamber, cuvette, tube, etc.) forinterfacing with flow measurement detector 28 of control assembly 10,flowrate control actuator interface 56 (soft flexible tube, such assilicone, polyurethane, polypropylene-based elastomer, etc.) forinterfacing with pinch head 100 of primary flowrate control actuator 22within control system assembly 10, and flow shutoff actuator interface58 (spring-loaded button, stopcock, pinch valve, etc.) for interfacingwith secondary flow shutoff actuator 30 of control assembly 10. Fluiddrainage cartridge 60 may further comprise drain tube 68 (silicone,polyurethane, polypropylene-based elastomer, etc.), connected at itsinlet end to detachable fitting 66 (luer fitting, neuro fitting, etc.)for interfacing with an implanted ventricular catheter, and connected atits outlet end to detachable drain bag 64 (polyethylene, PVC, etc.) forcollecting body fluids.

Patient interface assembly 50 may also include electrical cable 70between wearable pressure sensor subassembly 80 and fluid drainagecartridge 60, and a set of exposed conductive pads 54 (gold, copper,carbon, silver ink, etc.) on fluid drainage cartridge 60 for passingelectrical signals, data, power, etc. between patient interface assembly50 and control system assembly 10. In such embodiments, a correspondingset of spring contacts (pogo pins, battery-style contacts, etc.) incontrol system assembly 10 may interface with said conductive pads inthe patient interface assembly. Other embodiments of fluid drainagecartridge 60 may alternatively comprise a traditional electricalconnector that is manually inserted into a corresponding receptacle inthe control system assembly 10 by the user. Yet other embodiments mayreplace the physical electrical interface altogether by implementingwireless communication (Bluetooth, Wi-Fi, etc.) between patientinterface assembly 50 and control system assembly 10, or between patientinterface assembly 50 and a remote control system (cloud-based system,on-site or off-site server, smartphone or tablet-based application,etc.). In such arrangements, wearable pressure sensor subassembly 80 maybe powered with a battery or similar power source.

FIG. 5 is a line drawing that depicts an aspect of patient interfaceassembly 50 as it relates to the patient anatomy, wherein the proximalend of drainage tube 68 is separably connected via detachable fitting 66to an implanted ventricular catheter 206, and wherein wearable pressuresensor subassembly 80 is affixed directly to the patient's skinsubstantially proximate to a known anatomical marker (EAM, etc.) bysutures 120. In other embodiments, direct fixation of the wearablepressure sensor assembly may be accomplished by an adhesive patch(acrylic, etc.) with peel-off backing, or a separate liquid adhesive(cyanoacrylate, etc.) that is applied between the patient's skin and thewearable pressure sensor assembly housing. The patient fixation featuremay alternatively be on a separable component, such that the wearablepressure sensor assembly is affixed (snapped, fastened, hook-and-loopfastener, etc.) to/into the separable fixation component after it isaffixed (sutured, bonded, etc.) to the patient.

FIG. 6 and FIG. 7 depict alternate embodiments in which wearablepressure sensor subassembly 80 is constrained near an anatomical markerby means of a wearable device such as a headband or a hat (beanie, skullcap, etc.). Such wearable devices may be comprised of foam, silicone,fabric, hook-and- loop, mesh, gauze, etc.

FIG. 8 depicts an embodiment of wearable pressure sensor subassembly 80of patient interface assembly 50 (as depicted in FIG. 4 ), whereinpressure sensor subassembly 80 comprises a sensor array of two or morepressure sensors 126 and 128 for measuring a single body fluid pressure(ICP, blood pressure, bladder pressure, etc.) and an orientation sensor122 (accelerometer, tilt sensor, etc.) for detecting the orientation offlow channel 130. Wearable pressure sensor subassembly 80 may becontained (by bonding, mechanical fastening, over-molding, etc.) withina rigid (plastic, metal, etc.) or semi-rigid (silicone, polyurethane,etc.) enclosure 132, which includes integrated flow channel 130 with aninlet and outlet to which drain tube 68 is permanently affixed (UVbonding, solvent bonding, epoxy, etc.), and one or more suture points120 for attaching to a patient proximate to an anatomical marker (EAM,midaxillary, etc.). In various embodiments, the sensor array of wearablepressure sensor subassembly 80 may be constructed upon a suitablesubstrate (polyimide, polyester, FR-4, etc.) according to traditionalelectronics-fabrication methods known in the art. In various otherembodiments, sensors may be mounted directly onto enclosure 132 usingvarious other methods known in the art such as in-mold printedelectronics, conductive inks/epoxies, etc. In other aspects, pressuresensors 126 and 128 or orientation sensor 122 may produce digitalelectrical signals using a standard communications protocol known in theart (SPI, I2C, UART, etc.), or may produce an analog signal that isconverted to a digital signal by an analog-to-digital converter.

In some embodiments, wearable pressure sensor subassembly 80 mayadditionally include contact plates, a capacitive switch, or similarsensing element to detect whether the assembly is in contact with theskin. Such a feature may be useful for detecting certain faults, such aswhether the pressure sensor assembly has fallen off the patient and maynot be reading the proper pressure value.

FIG. 9A and FIG. 9B are schematic representations of wearable pressuresensor subassembly 80 according to certain embodiments of the presentdisclosure, wherein an orientation sensor (A) and a plurality ofpressure sensors (P1 and P2) are mounted at a fixed spacing distance (d)onto a rigid or semi-rigid member (B). FIG. 9A depicts wearable pressuresensor subassembly 80 in a horizontal orientation with respect togravity vector (g). FIG. 9B depicts wearable pressure sensor subassembly80 in a vertical orientation with respect to gravity vector (g).

Within certain aspects of this embodiment, the orientation sensordetects the orientation of wearable pressure sensor subassembly 80thereby facilitating calculation of an anticipated pressure differentialΔP according to the formula:

ΔP _(anticipated)=ρ(Δh)

wherein ρ is the fluid density (e.g., the density of CSF, saline, blood,urine, etc.) and Δh is the height differential between pressure sensorsP2 and P1 with respect to the gravity vector.

As depicted in FIG. 9A, when wearable pressure sensor subassembly 80 isoriented horizontally with respect to the gravity vector (g), thepressure readings of the plurality of pressure sensors (P1 and P2) aresubstantially equivalent because the height differential (Δh) betweenthe two pressure sensors (P1 and P2) is zero (i.e., Δh=0, soΔP_(anticipated)=0).

As depicted in FIG. 9B, when wearable pressure sensor subassembly 80 isoriented vertically with respect to the gravity vector (g), the pressuredifferential between the plurality of pressure sensors (P1 and P2) ismaximized because the height differential (Ah) between the two pressuresensors is also maximized (i.e., Δh=d, so ΔP_(anticipated)=ρd).

In any pressure sensor orientation other than horizontal or vertical,the height differential between the plurality of pressure sensors (P1and P2) will vary between 0 and d based on the vertical component ofpressure sensor orientation with respect to the gravity vector (g). Thecorresponding anticipated pressure differential will range fromΔP_(anticipated)=0 to ΔP_(anticipated)=ρd.

In certain embodiments of the control system algorithm, one or bothpressure sensors may be used to determine actual measured fluidpressure, while any substantial deviation between ΔP_(anticipated) (asdescribed above) and ΔP_(actual) (obtained directly via pressure sensorreadings) may be used by the system to detect pressure sensor faults(electrical failure, drift in sensor accuracy, bio-fouling, etc.).

It will be apparent to one skilled in the art that the currentdisclosure is applicable to the measurement of gauge or absolutepressure, since either may be accomplished depending on the type ofsensor used for P1 and P2, or the inclusion of separate atmosphericpressure sensor(s) outside the fluid path (such as in the control systemassembly) for the calculation of gauge pressure.

The disclosed approach provides two layers of redundancy. Firstly, sinceeach pressure sensor in wearable pressure sensor subassembly 80 islocated proximate to an anatomical marker for the fluid of interest, asecond pressure sensor provides a direct “backup” that may allow thesystem to continue operating in the event that either sensor isdetermined to no longer be functioning normally. Secondly, the systemmay detect very small amounts of drift in the accuracy of the wearablepressure sensor assembly and take appropriate action (such as notifyingthe user) before such errors become clinically relevant.

The disclosed approach differs from existing two-sensor systems, whereinone sensor measures the pressure in the target fluid line and a secondsensor measures the pressure in a separate reference line, and whereinboth pressure sensors are positioned at a location other than a relevantanatomical marker (e.g., in a pole-mounted console or hip-wornwearable). In such systems, the true pressure of the target fluid (e.g.,true ICP) is calculated as the difference between the pressure in adrain line and the pressure in a separate reference line.

Previously described two-sensor arrangements provide no redundancy andlimited opportunities for error-checking, leaving the patient vulnerableto sensor drift and similar faults. The co-location of two pressuresensors and an orientation sensor substantially proximate to a relevantanatomical marker as described in the current disclosure provides anunprecedented level of measurement accuracy and clinical safety.

It will be appreciated that wearable pressure sensor assembly 80 must besufficiently small and lightweight to facilitate attachment to certainanatomical markers (such as the EAM, which is located on the head) inorder to achieve practical use. As such, the use of sufficiently smallpressure sensors, which are suitable for extended contact with bodyfluids, and which are also of sufficient accuracy and precision as toenable clinical utility, is critical to achieving the disclosedembodiments. Furthermore, the spacing distance between the sensors mustbe sufficiently small as to facilitate a suitable overall footprint forthe assembly, which places further constraints on the precision of saidpressure sensors to enable useful drift detection as described elsewhereherein. For example, a spacing distance on the order of a fewcentimeters is only useful if the pressure sensors are able to resolvepressure differences on the order of a few millimeters of water (mmH2O).Such pressure sensors were unknown to the art until recently, renderingsuch embodiments impractical. However, due to recent technologicaldevelopments in the art, spacing distances (d) in the range of 1-2 cmare now possible, using tiny (2-3 mm wide) pressure sensors withprecision on the order of ±1 mmH2O, enabling practical embodiments ofwearable pressure sensor assemblies with an overall footprint in therange of 2-5 cm² that have the characteristics described herein.

3. Use and Configurations

FIG. 10 , FIG. 11 , and FIG. 12 depict several embodiments of thedisclosed body fluid management systems, which are configured forvarious clinical use cases.

FIG. 10 depicts one embodiment of the presently disclosed body fluidmanagement systems, which is configured for managing intracranialpressure (ICP) and cerebrospinal fluid (CSF) drainage, wherein patientinterface assembly 50 is connected to a ventricular catheter at theproximal end, and drainage collection reservoir 64 at the distal end,via drainage tube 68. The system of FIG. 10 may be configured viauser-controlled set points to activate primary flowrate control actuator22 and, thereby, allow drainage of CSF when ICP in excess of the setpoint is detected by wearable pressure sensor subassembly 80 attachedproximate to an anatomical marker (EAM) for the Foramen of Monro. Theembodiment represented by FIG. 10 may also find utility in themanagement of lumbar pressure (by affixing wearable pressure sensorassembly 80 near an anatomical marker appropriate for this application),and a variety of other body fluids and pressures within various bodycompartments.

In other embodiments, the disclosed system may additionally include aperistaltic (or similar) pumping mechanism and a connection to adetachable infusion source (infusion bag, infusion bottle, etc.). Thepumping mechanism may be configured to draw on the infusion source toperform periodic infusion operations, or to provide continuous orintermittent back-pressure for certain monitoring operations. Suchembodiments may find utility in a variety of clinical applications thatbenefit from back-pressure or periodic flushing. One example of such anarrangement is depicted in FIG. 11 , wherein patient interface assembly50 is configured to connect to an indwelling urinary catheter 201 at theproximal end, and to an infusion source 203 and drainage collectionreservoir 64 at the distal end, via bidirectional infusion and drainagetube 69. The system of FIG. 11 may be configured via user-controlled setpoints to activate the pumping mechanism to periodically flush thebladder and urinary catheter with a certain volume of saline.Alternatively, the system may be configured such that the pumpingmechanism infuses saline until a certain upper pressure threshold isdetected by wearable pressure sensor assembly 80 located substantiallyproximate to the bladder, at which point the pumping mechanism may bedeactivated to allow bladder drainage. In either case, the resultantflushing action mimics the body's natural urinary cycle by minimizingthe stagnant and low-flow conditions. Furthermore, repeated cleansing ofthe area may substantially dilute any bacterial units that begin tocolonize. Such arrangements may find utility in reducing the incidenceof bladder and urinary tract infections associated with uncontrolledurinary drainage and extended urinary catheterization typical in thecurrent clinical practice for management of patients during criticalcare.

The embodiment depicted in FIG. 11 may also find utility in monitoringthe pressure of various body cavities for compartment syndrome in a lessinvasive manner than direct implantation of a pressure transducer intothe cavity. For example, in the case of intra-abdominal pressuremonitoring, the system controller may utilize the infusion source andpumping mechanism to slightly inflate a patient's bladder with a smallquantity of saline (or similar fluid) and measure the resulting pressureresponse from the abdominal cavity by means of a wearable pressuresensor assembly located substantially proximate to an anatomical markerfor the bladder. The bladder pressure in such an arrangement may be usedas a minimally-invasive indicator of intra-abdominal pressure. Thesystem control assembly may be further configured to periodically pauseintra-abdominal pressure monitoring to allow substantially completedrainage of the bladder to ensure that appropriate urinary drainage ismaintained, then re-inflate the bladder to resume intra-abdominalpressure monitoring.

In other similar embodiments, the patient interface assembly may beconfigured to connect to an implanted venous catheter (central line) orimplanted arterial catheter (arterial line), and the control systemassembly may be configured to activate the pumping mechanism to flushthe blood connection line periodically or continuously with saline. Sucharrangements automate and improve upon clinical practice by ensuringpatency of the arterial or central line without constant clinicaloversight and maintenance and ensure that pressure sensor(s) located inthe line are not fouled by blood components or coagulated blood.

In certain embodiments, one or more additional pressure sensor(s) may beplaced within wearable pressure sensor subassembly 80 for addedredundancy, at a second anatomical marker of interest, on a separatefluid line for the measurement of multiple fluids (e.g., blood and CSFsimultaneously), or at strategic locations along one or more fluid lines(such as the high point of a fluid line where air bubbles are mostlikely to accumulate). Such arrangements may be warranted in certainapplications for enhanced patient safety, additional diagnostics orerror-checking, and/or additional clinical benefit or insight.

FIG. 12 depicts yet another embodiment of the presently disclosed fluidmanagement systems in which patient interface assembly 50 comprisesprimary fluid line 68 for connection to an implanted ventricularcatheter 206 at its proximal end and a detachable fluid drainagereservoir 64 at its distal end. In other aspects, patient interfaceassembly 50 further comprises secondary fluid line 205 for connection toan implanted arterial catheter 207 at its proximal end and an infusionsource 203 at its distal end. In other aspects, the patient interfaceassembly further comprises first wearable pressure sensor assembly 80 a,which is affixed to the patient substantially proximate to an anatomicalmarker appropriate for monitoring ICP (EAM), and second wearablepressure sensor assembly 80 b, which is affixed to the patientsubstantially proximate to an anatomical marker appropriate formonitoring blood pressure (fourth left intercostal space, etc.).

Each of the first and second wearable pressure sensor assemblies mayinclude an orientation sensor for monitoring patient movement/postureand error-checking pressure sensor readings as described elsewhereherein. The inclusion of multiple orientation sensors facilitates moredetailed tracking of patient posture (e.g., tracking patient trunkorientation independent of head orientation for more accurate real-timemodeling of the spinal column and associated CSF pressures in 3D space).Such information may be utilized by the system control assembly toautomatically adjust displayed values to reflect the true value of aparticular parameter more accurately at the anatomical point ofinterest, or for tracking of patient movement over time (e.g., forensuring a patient is moved with sufficient frequency to preventpressure injuries or for monitoring a patient that may be waking from acomatose or sedated condition).

In some embodiments, the first wearable pressure sensor assembly maymonitor only ICP, whereas the second wearable pressure sensor assemblymay monitor both ICP and blood pressure. Such an arrangement provides apressure reference for ICP that is normalized at the same elevation asthe blood pressure reference for accurate calculation of CPP. Inalternate embodiments, the second wearable pressure sensor assembly maymonitor blood pressure only.

In some embodiments, the patient interface assembly may be comprised ofa single integrated assembly, whereas in other embodiments the primary,secondary, and tertiary lines and their associated components may beseparate patient interface assemblies. In some embodiments, variousaspects of pumping mechanism 202 depicted in FIG. 11 and FIG. 12 may bedivided between patient interface assembly 50 and control systemassembly 10. In other embodiments, the system may be configured tomonitor or control two body fluids independently (for example, tomonitor intra-abdominal pressure via connection to an indwelling urinarycatheter on a first fluid line as described in FIG. 11 , and toindependently monitor ICP and provide controlled drainage of CSF on asecond fluid line as described in FIG. 10 ).

Embodiments of the disclosed fluid management systems such as thosedepicted in FIG. 12 may be further configured to use the data from thetwo wearable pressure sensor assemblies in combination to manage fluidpressure or drainage flowrate based on a derived parameter. For example,the system may be configured to manage CSF drainage according to CPPtarget setpoints and alarm thresholds, wherein instantaneous CPP iscalculated in real-time using the ICP and MAP values provided by thefirst and second wearable pressure sensor assemblies, respectively. Inother embodiments, the disclosed system may similarly be configured tomanage pressure or drainage flowrate of other body fluids based on otherderived parameters (spinal perfusion pressure, abdominal perfusionpressure, etc.). Systems that automatically manage fluid pressure anddrainage flowrate based derived parameters (such as CPP) represent asignificant advancement over the prior art, and enable exciting anduseful clinical applications that are not possible or practical withexisting technologies.

It will be understood that the disclosed body fluid management systemsmay thus be configured in a variety of ways for monitoring or managing avariety of fluids or anatomical subsystems, as may be deemed useful inclinical practice, without departing from the spirit of the disclosure.

The scope of the disclosure is thus indicated by the appended claimsrather than by the foregoing description, and all changes that comewithin meaning and range of equivalency of the claims are intended to beembraced herein.

What is claimed is:
 1. A body fluid management system, comprising: acontrol system assembly for real-time monitoring of a pressure of a bodyfluid, and a patient interface assembly, wherein said patient interfaceassembly comprises a tube and a wearable pressure sensor subassemblyin-line with said tube, wherein said tube is configured at one end forconnection to a patient-implanted catheter in direct fluid communicationwith said body fluid and configured at an opposite end for connection toan infusion source containing an infusion fluid, wherein said wearablepressure sensor subassembly is configured for attaching proximate to apatient anatomical marker, wherein said wearable pressure sensorsubassembly comprises at least one pressure sensor in direct fluidcommunication with said body fluid, wherein said control system assemblyis configured for monitoring changes in the pressure of said body fluidbased on inputs from the patient interface assembly, wherein saidcontrol system assembly is configured to display data, to makeadjustments to a flowrate of said infusion fluid, or to assert an alarmbased on user-selected operating modes and user-defined settings.
 2. Thebody fluid management system of claim 1 wherein said wearable pressuresensor subassembly further comprises an orientation sensor configured todetect an orientation of a body cavity containing said body fluid and amovement of said body cavity, wherein said control system assembly isconfigured for monitoring changes in patient movement or patientorientation.
 3. The body fluid management system of claim 2 wherein saidat least one pressure sensor comprises a first pressure sensor and asecond pressure sensor, wherein said first pressure sensor, said secondpressure sensor, and said orientation sensor are configured on a rigidmember, wherein said second pressure sensor is located at a fixedspacing distance from said first pressure sensor, wherein said controlsystem assembly is configured to calculate an anticipated differentialpressure between said first pressure sensor and said second pressuresensor based on said fixed spacing distance and orientation of saidrigid member as detected by said orientation sensor, wherein saidcontrol system assembly is configured to calculate an actualdifferential pressure between said first pressure sensor and said secondpressure sensor based on direct measured pressure of said body fluid,and wherein said control system assembly is configured for detectingdrift in the first pressure sensor or the second pressure sensor basedon a disparity between the anticipated differential pressure between thefirst pressure sensor and the second pressure sensor and the actualdifferential pressure between the first pressure sensor and the secondpressure sensor.
 4. The body fluid management system of claim 1 whereinsaid control system assembly comprises at least one fluid flow detectionand control subassembly.
 5. The body fluid management system of claim 4wherein said at least one fluid flow detection and control subassemblyis configured to monitor and control a flowrate of said infusion fluidand wherein said control system assembly is configured to calculatevolume over a user-selected time interval.
 6. The body fluid managementsystem of claim 5 wherein a static pressure of said infusion fluid isgreater than an average pressure of said body fluid, thereby producingan infusion pressure gradient, and wherein said fluid flow detection andcontrol subassembly comprises a valve configured to allow or disallowflow of said infusion fluid from said infusion source through said tubeand said patient-implanted catheter utilizing said infusion pressuregradient, thereby maintaining patency of said tube and saidpatient-implanted catheter.
 7. The body fluid management system of claim5, wherein said fluid flow detection and control subassembly comprises apump configured to pump said infusion fluid from said infusion sourcethrough said tube and said patient-implanted catheter, therebymaintaining patency of said tube and said patient-implanted catheter. 8.The body fluid management system of claim 1 wherein said control systemassembly comprises a graphical user interface configured to display apressure waveform.
 9. The body fluid management system of claim 1wherein said body fluid is blood and said patient anatomical marker isthe fourth intercostal space at the midaxillary line.
 10. The body fluidmanagement system of claim 1 wherein said body fluid is venous blood andwherein said control system assembly is configured for real-timemonitoring of central venous pressure.
 11. The body fluid managementsystem of claim 1 wherein said body fluid is arterial blood and whereinsaid control system assembly is configured for real-time monitoring ofmean arterial pressure.
 12. A body fluid management system, comprising acontrol system assembly and a patient interface assembly, wherein saidcontrol system assembly is configured to monitor real-time pressure of abody fluid and control drainage of said body fluid according to userselected parameters, wherein said patient interface assembly comprises abidirectional fluid line and a body fluid drainage line, wherein saidbidirectional fluid line is configured for connecting at its proximalend to a catheter inserted into a body compartment containing said bodyfluid, and for connecting at its distal end to an infusion sourcecontaining an infusion fluid, wherein said body fluid drainage line isconnected at its proximal end to said bidirectional fluid line, andconfigured for connecting at its distal end to a drainage reservoir,wherein at least one pressure sensor is disposed in said bidirectionalfluid line, configured to be in fluid communication with said bodyfluid, and configured to be located proximate to an anatomical markersuitable as an anatomical reference for monitoring a pressure of saidbody fluid and wherein said control system assembly is configured tocommunicate pressure values from the at least one pressure sensor. 13.The system of claim 12 wherein said control system assembly comprises atleast one fluid flow detection and control subassembly configured tomonitor and control a flowrate of a fluid and wherein said controlsystem assembly is configured to calculate volume over a user-selectedtime interval.
 14. The body fluid management system of claim 13 whereina static pressure of said infusion fluid is greater than an averagepressure of said body fluid, thereby producing an infusion pressuregradient, and wherein said fluid flow detection and control subassemblycomprises a valve configured to allow or disallow flow of said infusionfluid from said infusion source through said bidirectional line and saidpatient-implanted catheter utilizing said infusion pressure gradient.15. The body fluid management system of claim 13, wherein said fluidflow detection and control subassembly comprises a pump configured topump said infusion fluid from said infusion source through saidbidirectional line and said patient-implanted catheter.
 16. The bodyfluid management system of claim 12 wherein said at least one pressuresensor is disposed in a wearable pressure sensor subassembly furthercomprising at least one orientation sensor and an enclosure configuredfor attaching proximate to said anatomical marker.
 17. The system ofclaim 12 wherein said control system assembly comprises a graphical userinterface configured to display at least one pressure waveform.
 18. Thesystem of claim 13 wherein said at least one fluid flow detection andcontrol subassembly includes a first fluid flow detection and controlsubassembly and a second fluid flow detection and control subassembly,wherein said first fluid flow detection and control subassembly isconfigured for detecting and controlling flow of said body fluid,wherein said second fluid flow detection and control subassembly isconfigured for detecting and controlling flow of said infusion fluid.19. The system of claim 18 wherein said body fluid drainage volume is anet volume calculated as a difference between detected drainage volumeand detected infusion volume.
 20. The system of claim 12 wherein saidcontrol system assembly is configured to assert an alarm according toone or more user defined threshold(s) for body fluid drainage volume,body compartment pressure, pressure waveform, or infusion.
 21. Thesystem of claim 12 wherein said body cavity is the abdominal cavity,said body fluid is urine, and said body fluid pressure isintra-abdominal pressure.
 22. The system of claim 12 wherein one of saiduser selected parameters is target intra-abdominal pressure.
 23. Thebody fluid management system of claim 16 wherein said orientation sensoris configured to detect an orientation of a body cavity containing saidbody fluid and movement of said body cavity, and wherein said controlsystem assembly is configured for monitoring changes in patient movementor patient orientation.
 24. The body fluid management system of claim 23wherein said at least one pressure sensor includes a plurality of firstpressure sensors at a fixed spacing distance from one another, whereinsaid plurality of first pressure sensors and said at least oneorientation sensor are configured on a rigid member for detecting driftin said plurality of first pressure sensors based on a disparity betweenan anticipated differential pressure between said plurality of firstpressure sensors and an actual differential pressure between saidplurality of first pressure sensors.
 25. A body fluid management system,comprising a control system assembly and a patient interface assembly,wherein said control system assembly is configured to monitor real-timearterial blood pressure, real-time pressure of a body fluid, andreal-time perfusion pressure of a body compartment containing said bodyfluid, wherein said control system assembly is configured to controldrainage of said body fluid according to user selected parameters,wherein said patient interface assembly comprises a first fluid line anda second fluid line, wherein said first fluid line is configured forconnecting at its proximal end to a first catheter inserted into saidbody compartment and for connecting at its distal end to a body fluiddrainage reservoir, wherein said second fluid line is configured forconnecting at its proximal end to a second catheter fluidly connected toarterial blood and for connecting at its distal end to an infusionsource, wherein at least one first pressure sensor and at least onesecond pressure sensor are disposed in said first fluid line andconfigured to be in fluid communication with said body fluid, wherein atleast one third pressure sensor is disposed in said second fluid lineand configured to be in fluid communication with said arterial blood,wherein said at least one first pressure sensor is configured to belocated proximate to a first anatomical marker suitable as an anatomicalreference for monitoring a pressure of said body fluid, wherein said atleast one second pressure sensor and said at least one third pressuresensor are configured to be co-located proximate to a second anatomicalmarker suitable as an anatomical reference for monitoring arterial bloodpressure, wherein said control system assembly is configured to displaypressure values from the at least one first pressure sensor as the truepressure of body fluid in said body compartment, wherein said controlsystem assembly is configured to display pressure values from the atleast one third pressure sensor as the true pressure of said arterialblood, and wherein said control system assembly is configured tocalculate and display perfusion pressure as a difference betweenpressure values from the at least one third pressure sensor and pressurevalues from the at least one second pressure sensor.
 26. The body fluidmanagement system of claim 25 wherein said at least one first pressuresensor is disposed in a first wearable pressure sensor subassemblyfurther comprising a first orientation sensor and a first enclosureconfigured for attaching proximate to said first anatomical marker, andwherein said at least one second pressure sensor and said at least onethird pressure sensor are disposed in a second wearable pressure sensorsubassembly further comprising a second orientation sensor and a secondenclosure configured for attaching proximate to said second anatomicalmarker.
 27. The system of claim 25 wherein said control system assemblycomprises at least one fluid flow detection and control subassembly. 28.The system of claim 27 wherein said at least one fluid flow detectionand control subassembly includes a first fluid flow detection andcontrol subassembly and a second fluid flow detection and controlsubassembly, wherein said first fluid flow detection and controlsubassembly is configured for detecting and controlling flow of saidbody fluid, wherein said second fluid flow detection and controlsubassembly is configured for detecting and controlling flow of saidinfusion fluid.
 29. The system of claim 28 wherein said first fluid flowdetection and control subassembly comprises a valve configured to allowor disallow flow of said body fluid from said first catheter to saidbody fluid drainage reservoir and wherein said second fluid flowdetection and control subassembly comprises a pump configured to pumpsaid infusion fluid from said infusion source through said second fluidline and said second catheter.
 30. The system of claim 25 wherein saidcontrol system assembly comprises a graphical user interface configuredto display at least one pressure waveform.
 31. The system of claim 25wherein said perfusion pressure is cerebral perfusion pressure, saidbody cavity is the cranial cavity, said body fluid is cerebrospinalfluid, and said body fluid pressure is intracranial pressure.
 32. Thesystem of claim 25 wherein said perfusion pressure is spinal cordperfusion pressure, said body cavity is the spinal cavity, said bodyfluid is cerebrospinal fluid, and said body fluid pressure is lumbarpressure.
 33. The system of claim 25 wherein one of said user selectedparameters is target perfusion pressure.
 34. The system of claim 25wherein one of said user selected parameters is target intercranialpressure.
 35. The system of claim 25 wherein one of said user selectedparameters is target body fluid drainage volume.
 36. The system of claim25 wherein said control system assembly is configured to assert an alarmaccording to one or more user defined threshold(s) for perfusionpressure, body fluid drainage volume, body fluid pressure, bloodpressure, or pressure waveform.
 37. The body fluid management system ofclaim 26 wherein said at least one first pressure sensor includes aplurality of first pressure sensors at a fixed spacing distance from oneanother, wherein said plurality of first pressure sensors and said firstorientation sensor are configured on a rigid member for detecting driftin said plurality of first pressure sensors based on a disparity betweenan anticipated differential pressure between said plurality of firstpressure sensors and an actual differential pressure between saidplurality of first pressure sensors.
 38. The body fluid managementsystem of claim 26 wherein one or both of said second pressure sensor orsaid third pressure sensor each include a plurality of pressure sensorsat a fixed spacing distance from one another, wherein said plurality ofsecond or third pressure sensors and said second orientation sensor areconfigured on a rigid member for detecting drift in said plurality ofsecond or third pressure sensors based on a disparity between ananticipated differential pressure between said plurality of second orthird pressure sensors and an actual differential pressure between saidplurality of second or third pressure sensors.
 39. The system of claim28 wherein said first fluid line is configured for bidirectional flowand wherein the distal end of said first fluid line is furtherconfigured for connection to a second infusion source.
 40. The system ofclaim 39 wherein the at least one fluid flow detection and controlsubassembly further comprises a third fluid flow detection and controlsubassembly for detecting and controlling flow from said second infusionsource into said first fluid line.
 41. The system of claim 40 whereinsaid perfusion pressure is abdominal perfusion pressure, said bodycavity is the abdominal cavity, said body fluid is urine, and said bodyfluid pressure is intra-abdominal pressure.